This invention relates generally to network systems and more particularly to a virtual dial-up system used for accessing a private local network through an internet access service.
FIG. 1 is a prior art internetwork system 12 which includes multiple dial-up network access servers (NAS) 14 also referred to as points of presence (POPs). The POPs 14 can be located at different geographical locations around the world. An internet service provider (ISP) operates multiple POPs 14 through a backbone network 16. The ISP network 16 is connected to an internet infrastructure, referred to generally as internet 18. Different clients 26 dial into a POP 14 in order to access the internet through the ISP network 16.
Local Area Networks (LANs) 22 are typically operated by private companies and include multiple local clients 26. The LAN 22 is connected to internet 18 through a home gateway 20. The home gateway 20 includes a firewall 28 that prevents unauthorized external access into the private network 22 through internet 18. While some access is possible from outside the firewall (e.g., electronic mail), resources such as network databases and application programs are only accessible by clients located behind the firewall 28.
An authorized client may need to access files and other resources on network 22 from remote locations, such as when working at home or while on sales trips. Privately operated POPs 24 provide the remote clients with a direct dial-up capability to network 22. Since the POP 24 is located behind firewall 28, a remote client can dial into POP 24 and gain full access to resources on network 22.
In many instances, it is more cost effective for companies to outsource dial-up service to general internet service providers, such as ISP 16. However, the firewall 28 in home gateway 20 denies access to remote clients that attempt to access LAN 22 through a general internet service provider.
Different network protocols may be used within the internet infrastructure and within the private network 22. For example, an Internet Protocol (IP) is typically used at the network protocol level to send information through the internet 18. However, private networks 22 may use any one of a variety of network protocols including IP, IPX, Appletalk, etc. When a remote client dials into a POP 14, the ISP dynamically assigns an IP address to the remote client 26. Thus, the remote client may be denied access by home gateway 20 because the IP address assigned by the ISP network 16 is not one of the authorized addresses in the LAN 22. The remote client may also be forced by the ISP to use an IP protocol incompatible with the local network 22. Because the IP protocol and the local LAN protocol are incompatible, the remote client is prevented from accessing resources on LAN 22.
Accordingly, a need remains for remote client access to private networks through internet service providers while maintaining security from unauthorized internet users.